Condensation of Ammonia with Phenols

[Anders Hoveland]

Rosorcinol (1,3-dihydroxy-benzene) can be converted to phloroglucinol (1,3,5-trihydroxy-bezene) by [heating] fusion with solid sodium hydroxide. the reaction also releases hydrogen gas.

"THE LIBERATION OF HYDROGEN FROM CARBON COMPOUNDS", Shipley Fry, Else L. Schulze, Helen Weitkamp

J. Am. Chem. Soc., 1924, 46 (10), pp 2268–2275

 

 

The literature extensively describes the preparation of phloroglucinol by hydrolysis of 1,3,5-triaminobenzene in the presence of concentrated hydrochloric acid.

 

hydrolysis of 1,3,5-triaminobenzene to give phloroglucinol, mention may be made of U.S. Pat. No. 4,115,451. That patent recommends hydrolysis of 1,3,5-triaminobenzene in an excess of concentrated hydrochloric acid at a temperature of 100 to 200° C., to end up with phloroglucinol. This hydrolysis step is followed by a step of extraction with an acetic ester. The extracted phase containing the phloroglucinol crystallizes after cooling.

 

From the foregoing results, it appears that phloroglucinol, a trihydric phenol, reacts more energetically with aromatic amines than the dihydric phenols [such as 1,3-dihydroxybenzene], which in turn are more reactive than the monhydric compounds [example, phenol].

 

In view of the complete analogy between the action of ammonia and the substituted amines, it seems probable that phloramine, the product of the action of ammonia on phloroglucinol, is also a derivative of trihydroxybenzene, and not of the secondary phloroglucinol, as indicated by Baeyer (Abstr. 1886, 350).

Journal of the Chemical Society, Volume 60

(Great Britain), p191

 

 

Phloramine- A compound produced by the action of ammonia on phloroglucin.

C5H6O3 + NH3 --> C6H7NO2 + H2O

A dictionary of chemistry and the allied branches of other sciences, Volume 4, p488

 

 

It would appear that whereas phloroglucin[ol] is the tautomer of 1,2,3-trihydroxy-benzene, phloroglucin, which is a partial imine of a tri-ketone, is the tautomer of 3,5-dihydroxy-aniline.

 

The conversion of phenol into aniline proceeds under very drastic conditions (350-450°C, 50-60 bar) and the substitution of one hydroxyl group in resorcinol by an amino group

occurs quite readily at 200°C, whereas phloroglucinol gives 3,5-dihydroxyaniline and 3,5-diaminophenol in almost quantitative yield under very mild conditions (long storage at room temperature with ethanolic solution of ammonia).

 

It was [calculated] that the enolic form, 1,3,5-benezenetriol, is by far more stable than the keto form, 1,3,5-cyclohexanetrione. On the other hand, the latter is more abundant in the phloroglucinol system than is the keto form of phenol (2,4-cyclohexadien-1-one)

 

The picture (on page 718, figures 15 and 16) clearly shows that hydroxylamine condenses with phloroglucinol to form the tri-oxime of cylcohexane.

 

Chemistry of Phenols, Part 2

Zvi Rappoport, p717-718

http://books.google.com/books?id=0pVQgwt5ODoC&pg=PA718&lpg=PA718&dq=phloroglucinol+3,5-dihydroxyaniline&source=bl&ots=U_n0bCoPSk&sig=YeAbhRflCHg1elC-nKvmDKBLZCM&hl=en&ei=qpfeTr3TFu7ciQLH84WEDA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCAQ6AEwAA#v=onepage&q=phloroglucinol%203%2C5-dihydroxyaniline&f=false

 

 

 

I cannot find any references about further condensing 3,5-diaminophenol with ammonia to form 1,3,5-triaminobenzene, although I did find a reference to the reverse reaction,

The most convenient method of preparation is the hydrolysis of the hydrochloride of 1:3:5-triamino- benzene by prolonged boiling with water.

Chemistry of carbon compounds: a modern comprehensive treatise, edited by E. H. Rodd, p483; specific reference made to H. Weidel and J. Pollak, Monatsh., 1900, 21, 20

 

hydrolyse 1:3:5-triaminobenzene with 5% HCl and obtain 3:5-diaminophenol.

Reports on the progress of applied chemistry, Volume 33, p74

 

It may be possible that a third amino group cannot be added. But the fact that hydroxylamine can fully condense with 1,3,5-trihydroxybenzene suggests that ammonia may also be able to react likewise.

Edited December 6, 2011 by Anders Hoveland